Compounds having the structural formula ##STR2## wherein X can be alkyl, n can be 0, 1, or 2, and R.sub.1 can be phenyl or substituted phenyl are described in Japanese Patent Application No. 84632-1974 as being intermediates for the preparation of herbicidal compounds of the formula ##STR3## wherein R.sub.1, X, and n are as defined above and R.sub.2 is alkyl, alkenyl, or alkynyl. Specifically taught herbicidal compounds of this latter group are those where n is 2, X is 5,5-dimethyl, R.sub.2 allyl and R.sub.1 is phenyl, 4-chlorophenyl or 4-methoxyphenyl.
The precursor intermediates for these three specifically taught compounds have no or almost no herbicidal activity.